Drainage catheters are used to drain excess fluid from the body of a patient. For example, drainage catheters may be suitable for draining abscesses, biliary system fluids, excess peritoneal fluid (ascites), and the urinary tract.
Drainage catheters are often made of flexible materials such as polyurethane, polytetrafluoroethylene (PTFE), or any other material known in the art. The distal end of a drainage catheter may be tapered, slightly beveled or blunt. The use of a flexible material and a tapered, slightly beveled distal or blunt end minimizes damage to the patient's tissue while the catheter is in place. The distal end of a drainage catheter is also frequently curved to prevent the distal end of the catheter from moving once placed in the desired location in a patient's body. This curve is called a “pig-tail.”
In order to drain excess fluid, the catheter must be inserted into the body of a patient at the desired location. The catheter itself is generally inserted into the body through an incision. The incision is often made by first nicking the skin with a sharp instrument such as a scalpel and then pushing a needle or cannula through the opening formed by that nick. The process of inserting the catheter is accomplished by inserting a needle through the catheter until the sharp distal end of the needle protrudes beyond the distal end of the catheter. The needle and catheter are then pushed through the nick in the patient's skin and into the body until they reaches the site of the fluid to be drained. Once in place, the needle is withdrawn through the drainage catheter so that it is no longer protruding beyond the distal end of the catheter. The catheter may then be used to drain the fluid. The withdrawal of the sharp needle into the body of the catheter prevents accidental pricking or irritation to the patient.
When the needle or cannula is threaded through the lumen of the catheter prior to insertion of the drainage catheter, there is a risk that the sharp distal end of the needle or cannula will damage the interior of the catheter. There is a particularly high risk of a needle damaging drainage catheters having a curved “pig-tail” at the distal end. The needle may puncture the catheter or “shave” the interior walls of the catheter. It is undesirable to “shave” the interior of the catheter wall because this weakens the catheter. In addition, the fine shavings produced by this damage may result in blockage to the drainage catheter. The shavings may also make their way into the patient.
In order to prevent damage to the interior of the drainage catheter, an obturator with a rounded distal end is often inserted into the lumen of the needle or cannula before the needle is threaded through the catheter. Obturators known in the art are typically straight and have a rounded distal end. An obturator is generally inserted through the lumen of the needle or cannula so that the rounded distal end of the obturator is distal to the distal end of the needle or cannula. Once the obturator is in place, the obturator-needle assembly may be threaded through the lumen of the drainage catheter. The rounded distal end of the obturator attempts to protect the interior of the drainage catheter from being damaged by the sharp distal end of the needle.
Despite the use of obturators in the prior art, “shaving” of the interior of the catheter still occurs in some instances.